Catherine Turon

The HIPPARCOS INCA Database

The Hipparcos INCA database was created at the initiative of D. Morin and has been developed by F. Arenou and D. Morin, with the help of M.-O. Baylac, M. Marouard, M. Mekkas, and A. Sellier, under the scientific supervision of A. Gomez, F. Crifo and C. Turon. The reconversion of the database from the Orsay Computer center to the Ultrix DEC system presently used was done in collaboration with the SIMBAD team at Strasbourg, mainly by F. Arenou and D. Boumghar.

Science with GYES: a multifibre high-resolution spectrograph for the prime focus of the Canada-France-Hawaii Telescope

We present the scientific motivations for GYES: a high multiplex (of the order of several hundred), high resolution (about 20 000), spectrograph to be placed at the prime focus of the CFHT. The main purpose of such an instrument is to conduct a spectroscopic survey complementary to the Gaia mission. The final Gaia catalogue (expected around 2020) will provide accurate distances, proper motions and spectrophotometry for all the stars down to a magnitude of 20. The spectroscopic instrument on board the Gaia satellite will provide intermediate resolution (R=11 500) spectra for stars down to the 17th magnitude. For the fainter stars there will be no radial velocity information. For all the stars the chemical information will be limited to a few species. A multifibre spectrograph at the prime focus of the CFHT will be able to provide the high resolution spectra for stars fainter than 13th magnitude, needed to obtain both accurate radial velocities and detailed chemical abundances. The possible use of GYES will not be limited to Gaia complementary surveys and we here describe the potentialities of such an instrument. We describe here how the scientific drivers are translated into technical requirements. The results of our on-going feasibility study are described in an accompanying poster.

The Tycho-2 Catalogue: a reference for astrometry and photometry. Combining the most modern and the oldest astrometric data - Commentary on: Høg E., Fabricius C., Makarov V. V., et al., 2000, A&A, 355, L27

The main Hipparcos mission, the first astrometric satellite ever launched, was included in the ESA Science Programme in March 1980. It was aiming at the fundamental task of measuring the angular positions and displacements of about 100 000 pre-selected stars to obtain a large set of distances and proper motions that are more accurate and homogenous than ever before and that drastically improve our knowledge of the structure, kinematics, and dynamics of the local part of our Galaxy and of the various types of stars present there (see for example Turon & Arenou 2008). The resulting catalog was published in 1997 (Perryman et al. 1997), and it indeed opened the way to a wide variety of astrophysical applications (Perryman 2009).

DIVISION IX: COMMISSION 30: RADIAL VELOCITIES

The meeting was attended by the President and Vice-President of the Commission, along with approximately 15 other members. The President reported on the election of new officers that took place at the end of March 2012, for four new members of the Organizing Committee as well as a new Vice-President, and thanked the outgoing members. Tomaz Zwitter (Slovenia) was elected as the new VP (2012–2015), and the new OC members for the period 2012–2018 are Alceste Bonanos (Greece), Alain Jorissen (Belgium), David Katz (France), and Matthias Steinmetz (Germany). The current VP, Dimitri Pourbaix, became the President through 2015.

ESA Space Science Programme, Cosmic Vision 2015-2025 , for astrophysics

After a brief description of the ESA Science Programme, the long-term plan for Astrophysics is described, as well as possible strategies for its implementation.

COMMISSION 30: RADIAL VELOCITIES

This three-year period has seen considerable activity in the Commission, with a wide range of applications of radial velocities as well as a significant push toward higher precision. The latter has been driven in large part by the exciting research on extrasolar planets. This field is now on the verge of detecting Earth-mass bodies around nearby stars, as demonstrated by recent work summarized below, and radial velocities continue to play a central role.

Distance and Age of M92 From Hipparcos Subdwarfs

The parallax data gathered by Hipparcos for field subdwarfs allow a muchmore precise determination of globular cluster distances by direct sequencefitting than was previously possible. We determined the distance and age ofthe old, representative globular cluster M92 from a set of more than 500 subdwarf candidates with Hipparcos parallaxes. Precise [Fe/H] values were derived using the equivalent width of the CORAVEL cross-correlation function. Our best estimate of the distance of M92 is ( m — M) v = 14.67 ± 0.08 (including binaries with a statistical correction) or ( m — M) v = 14.74 ± 0.08 (classic treatment, i.e. excluding binaries). The agreement of the cluster sequence with the position of extreme metal-poor field subdwarfs is remarkable [figure, left]. The distance found is slightly higher than previously thought. The corresponding ages, derived by comparing the luminosity of the turnoff and subgiant-branchstars with up-to-date evolution models [figure, right], are 14±1.2 Gyr or 13±1.2 Gyr respectively, implying a minimum age of 13 Gyr for the Universe. Other authors have claimed that larger distances, and smaller ages, resulted from Hipparcos subdwarf parallaxes. Although there are some differences in the data sets used by each author, the main difference resides in the treatment of systematic and selection biases. We have examined at some length the biases affecting the determination of the mean luminosity of a set of subdwarfs selected in the usual way. By means of Monte Carlo simulations, we show that selection biases act in a direction opposite to the classic Lutz-Kelker bias affecting parallax data, and that they can be dominant. The biases introduced are of the order of 0.1 mag. It is pointed out that, now that the whole Hipparcos catalogue is available, we shall be able to greatly reduce the systematic biases by refining the fitting procedure. Firstly, by imposing no [Fe/H] limits and fitting the subdwarf locus for all [Fe/H] values at the same time. Secondly, by imposing no parallax error limit and fitting the data in parallax space instead of magnitude space (comparing observed parallaxes directly with parallaxes predicted from the models).

Scientific Contents of the Hipparcos Input Catalogue

The Hipparcos Input Catalogue -hereafter called HIC- (Turon et al. 1992a, Turon et al. 1994) contains the observing programme of the Hipparcos mission: 118 000 preselected stars, 48 minor planets and three satellites of major planets. These objects were selected on the grounds of more than 200 scientific programmes proposed by the world-wide astronomical community, and dealing with a large variety of astronomical and astrophysical topics. It contains the most up-to-date, comprehensive and homogeneous data and information related to these programme stars, collected during the years 1981–1990 by the INCA Consortium (Hipparcos INput CAtalogue consortium)